This invention relates to a.c. arc welders and particularly to a novel arrangement of primary and secondary transformer coils formed of relatively economical, flat, aluminum strip which achieves improved heat dissipation and coil rigidity, and to a novel and convenient means of positioning and releasably locking a flux shutting core in slidably adjusted positions to steplessly vary the current output.
Flux shunting cores to vary the transformer output are disclosed in U.S. Pat. Nos. 2,243,169, 3,394,332, and 3,523,272. U.S. Pat. Nos. 3,394,332 and 3,523,272 disclose pivotally mounted flux shunting cores, and U.S. Pat. No. 2,243,169 diagrammatically illustrates two slidably movable flux shunting cores arranged to variably shunt the flux generated by the primary coils of two adjacent transformers. Further, U.S. Pat. No. 3,523,272 discloses primary and secondary transformer coils formed of flat aluminum strip.
It has been found essential in the construction of a.c. arc welder transformers employing a novable flux shunting core that means be provided to suitably lock the movable core in adjusted positions against objectionable or even destructive vibrations at the a.c. power source frequency. It has also been found highly desirable to provide means whereby an operator may conveniently release, adjust, and adequately lock the movable shunting core with one hand and little physical effort while holding a welding electrode in the other. Moreover, it has been found that the employment of economical and relatively soft flat aluminum strip, suitable for forming the flat primary and secondary transformer coils, presents the problem of providing adequate coil rigidity to withstand vibration forces and heating under operating conditions, without lateral movement or distortion, while at the same time providing improved cooling to preclude excessive heating.
One of the objects of the invention is to provide a generally new and improved a. c. arc welder in which the primary and secondary transformer coils are formed of economical aluminum strip and in which a slidably movable flux shunting core gradually varies the output.
A further object is to provide an a.c. arc welder in which a novel arrangement of flat primary and secondary transformer coils formed of aluminum strip on a rectangular frame core provides coil rigidity, substantially improved cooling with higher current output relative to open circuit voltage, and permits the slidable adjustment of a flux shunting core between the primary and secondary coils.
A further object is to provide novel and convenient means for locking, releasing, adjustably positioning, and slidably guiding a flux shunting core.
Further objects and advantages will appear from the following description when read in connection with the accompanying drawings.